1. Field of the Invention
This invention refers to a method and an apparatus for producing rapid movement and smooth braking as well as precise final positions of a movable robot arm. When the robot is in use, the robot arm is capable of being set into a plurality of positions successively, with said rapid movement, smooth braking, and precise final position being achieved in each individual position into which the arm is set.
2. Description of the Prior Art
When robot arms are utilized in industry, the intention is that a tool or an object, respectively, located at one end of the robot arm, is to be capable of performing predetermined operations when the arm is disposed in different longitudinal displacement positions. The robot arm must be able to move rapidly between these positions and to stop smoothly at each position, as braking of impact type causes poor precision with regard to positioning and uncertain reproducibility. The robot arm has a certain weight in itself, and the tool or object, respectively, at its end may also be heavy. In order to produce rapid movement and smooth braking as well as high reproducibility of the final position it is basically necessary to solve the problem of rapidly and progressively reducing the level of the kinetic energy of the robot arm, tool and object.
In utilizing one or two end positions of a device driving the robot arm, for example one or both of the end positions of a hydraulic cylinder, with the robot arm being set into this end position or these end positions, no difficulties arise, but if the robot arm is to be stopped at a plurality of intermediate positions it becomes very difficult to achieve good reproducibility and concurrent smooth braking.